Electrolytic condenser



Filed Oct. 26, 1937 INVENTQR f 'amuei 15915211 ATTORNEY Patented May 7,1940 UNITED STATES PATENT OFFICE 10 Claims.

This invention relates to electrolytic condensers. A general object isthe provision of electrolytic condensers of both dry and wet type whichare of new, novel and simpledesign, which can be produced-at a low cost,which provide maximum capacitance for a given volume and which to alarge extent may be manufactured by machine with a minimum of labor.

An object of the invention is the provision of an electrolyticcondenserin which the anode, cathode and spacer are combined in a unitarystructure.

A further object is the provision of an electrolytic condenser in whichboth electrodes. and the spacer are united in a single .woven cloth.

Another object is the provision of a unitary electrolytic cell structurecomposed of a woven cloth, the shoot of which is insulated from thewarp.

Still another object is to provide a unitary cathode-anode spacerstructure by weaving together two metal strands insulated from eachother by a porous spacer wound around at least one of said strands.

5 Another object is the provision of an electrolytic device having twoor more capacitances in a single unit.

A further object is to provide a multi-capacitance condenser in the formof woven cloth having a plurality of separated warps serving as anodesin relation to and electrically insulated from the shoot strands,serving as a common cathode.

Further objects will be apparent from the disclosure and from thedrawing, in which,

Fig. 1 is a face view of a unitary cathode-anode spacer constructionmade according to this invention;

Fig. 2 is a view showing in detail the arrange- 40 ment of cathode,anode and spacer;

Fig. 3 is a face view of a structure which comprises two capacitances'ina single unit;

Fig. 4 is a view ofthe structure shown in Fig. 1 in semi-rolled form,and

Fig. 5 shows a condenser mounted within a container.

Dry electrolytic condensers as heretofore commercially. manufacturedcomprise two cooperating electrodes of film forming metal such as -5oaluminum or tantalum, at least one of the electrodes havingelectrolytically formed on its surface an immeasurably thin film ofoxide which serves as the dielectric. The electrodes are separated byabsorbent spacers such as gauze, paper, 55 non-fibrous sheet celluloseor combinations of these spacers, and the electrolyte employed is aviscid film maintaining composition which may be a heavy paste, or onlyslightly viscous. As the condensers are usually constructed in rollform, at least two spacers are required in order to preventshort-circuiting of the electrodes. Thus, the manufacture of thecondenser requires the handling of two rolls of foil and two or morerolls of spacer, such as Cellophane, paper, gauze, et cetcra. If thecondensers are wet Wound, 10 that is, if the foils and spacers are drawnthrough the viscid electrolyte in the winding process, difiiculty issometimes encountered in lining up the rolls and in preventingtelescoping. If the condensers are dry wound and thereafter im- 5pregnated with the electrolyte, the tight winding of the foils andspacers retards the absorption of the viscid electrolyte by the spacerand makes necessary a long immersion period and in some cases, acentrifuging operation. 20

In my co-pending application bearing Serial Number 162,401, filedSeptember 4, 1937, of which this application is acontinuation in part, Idescribe the use of woven metal cloth as an electrode in order to obtaina high capacitance in a small area. I also describe in that case, astructure comprising a cloth woven from cotton-covered aluminum wire,the cotton winding allowing an increased effective area and capacity andeliminating the use of separate spacer elements. 30

In the present invention I utilize-cloth having a weave somewhat similarto that shown in my aforesaid co-pending application, but go a stepfurther and provide cathode, anode and spacer in a single wovenstructure. In this new condenser 35 the shoot may be composed ofelectrolytically oxidized aluminum wire which serves as the anode andthe warp may be composed of double cottoncovered aluminum wire, or thewarp may be the anode and the shoot the cathode. The two strands arewoven into a close mesh cloth, preferably in ribbon form, about twoinches wide with a selvage edge. The anode threads should be veryclosely spaced in order to aiford the maximum eifective area.

The warp may to advantage be composed of large diameter wire when theunit is used on direct current. For example, I have used as warp strands.010 inch diameter cotton-covered aluminum wire, which strands serve asthe cathode, and for the anode or shoot wire I have used .005 inchdiameter aluminum with a 200 x24 twill weave. In some cases a plainweave is desirable, while in other cases a twill weave is of advantage.

If the condenser is to be used on alternating combination of paper andCellophane",

current, the warp and the shoot are both electrolytically oxidized orformed and are 0! equal area so as to avoid assymetrical conductiveeffects.

The manufacture of the condenser section is exceedingly simple, thewoven ribbon being merely wound into roll form and immersed in theelectrolyte.

While aluminum wire is considered the most suitable film-formingmaterial, other metals, such as tantalum, magnesium or alloys of thesemetals with aluminum, may be utilized. I prefer to form oroxidize thewire prior to the time it is woven into the cloth, but the forming may,of course, take place after the weaving. To increase the capacitance ofthe unit the wire prior to forming, may be etched in a manner well knownto the art, for instance, by immersing in a bath of copper-chloride orin a mixture of hydrofluoric and hydrochloric acids.

Cotton is the preferred material for use as a spacer element and as anelectrolyte-absorbing material but other spacers capable of being woundor wrapped upon the wire may be used, for example, Cellophane, paper,rayon or a cemented together with a. conductive cement. Thecotton-covered wire may, i-fdesirable, be sized with methyl celluloseplasticized with a glycol, thus providing a film between the cottonfibres, having properties somewhat akin to Cellophane.

While in most cases it will be desirable to cotton-cover only one of theelectrodes, namely, the warp, both the warp and shoot may beadvantageously covered for some purposes. Where both electrodes arecovered, the maximum quantity of electrolyte is held in contactwith theelectrodes. are cotton-covered, plain thin aluminum foil can withadvantage be used in contact with each side of the cloth in order toreduce the current path length and thus maintain a low power factor.Such a sheet of foil can also be used to advantage on direct currentcondensers where the anode is a cotton-covered shoot and the cathode isthe plain aluminum wire warp. In the latter structure the foil would beconnected to the warp.

Where it is desired to provide diiferent values of capacitance in thesame unitary condenser structure, the warp or the shoot may be utilizedas a common cathode. mon cathode, the selvaged edge with the shoot orbare wire is cut and several strands of the shoot wire pulled out, thuselectrically-separating the shoot weave. Contact is made with the shootwires brought out from the various separated sections, thus allowing asimple and economical method of obtaining multi-capacitance units.

The structure may also be used for polarized cells ofthe iron or nickeltype, employing alka- If the warp is the com-.

Where both warp and shoot wires line electrolytes which operate belowthe decom-' position potentials of the electrolyte.

In order to more fully describe certain forms of the invention,reference is made to the attached drawing. In Fig. 1, the unitarystructure I, comprising the anode, cathode and spacer, has been partlycutaway at one end section to provide anode tab 2, and at the oppositesection cathode terminal post I, which serves as the common cathode foranodes I. and 'b.

While the invention is especially useful in connection with dry orplastic-type electrolytes of the type described in my United StatesLetters Patent 1,710,073; 1,714,191; 1,891,207; 1,918,716; 1,918,717, etal., the structures shown or modifications thereof may be advantageouslyused in wet electrolytic condensers, especially where it is desired toprovide two or more capacitances in a single unit. For instance, thestructure shown in Fig. 3 may be modified to substitute enameled copperwire for the cotton-covered aluminum cathode 3, the enameled insulationbeing removed at the terminal of the wire to provide contact withterminal member 4 and the electrolyte.

Fig. 4 shows the condenser structure of Fig. 1 in semi-rolled form.

InFig. 5' a condenser section III, comprising the structure illustratedin Fig. 1 in roll form has been impregnated and wrapped with varnishedpaper II, and mounted in container l2, from which it is insulated bypitch l3. The container' is sealed by Bakelite top l6, through which arebrought out terminals l4 and I5.

The structure of the condenser lends itself readily to a simpleimpregnation process. Due to the unitary structure, no difflculty isexperienced in thoroughly impregnating every part of the condenser, anddue to the close association of the spacer element with the film-formingelectrodes a maximum quantity of electrolyte is always in contact withboth cathode and anode. This is, of course, particularly true when aviscous fluid electrolyte of the glycol-ammonium .borate type is used.As not only is this type of electrolyte thoroughly absorbed .in thecotton spacer, 'but due to its viscous character and the woven surfaceof the cathode-anode structure, it tends to adhere to all parts of thecondenser unit.

Having described my invention, what I claim as new and desire to secureby Letters Patent, is:

1. An electrolytic 'condenser comprising an aluminum cloth, the shootconstituting one electrode and the warp the other electrode, a spaceraround' at least one of said electrodes so as to insulate it from theother electrode, and an electrolyte.

2. An electrolytic condenser comprising a metal cloth, said clothcomprising metal wires at least one of which is a film forming metal,the shoot constituting one electrode and the warp the other electrode, aspacer around at least one of said electrodes so as to insulate it fromthe other electrode, and an electrolyte in said spacer and in contactwith both electrodes.

3. An electrolytic condenser comprising a metal cloth, the shootconstituting one electrode and the warp constituting the otherelectrode, an electrolyte permeable cellulose spacer around at least oneof said electrodes so as to insulate it from metallic contact with theother electrode,

and an electrolyte in said spacer in contact with both electrodes.

4. An electrolytic condenser comprising a metal cloth, the shootconstituting one electrode and the warp constituting the otherelectrode, an electrolyte permeable cellulose spacer around at least oneof said electrodes so as to insulate it.

forming metal wire being chemically etched so as to increase itscapacity and having a dielectric oxide film formed on said etchedsurface, a spacer around at least one of said electrodes so as toinsulate it from metallic contact with the other, and an electrolyte insaid spacer and in contact with both electrodes.

6. An electrolytic condenser comprising an aluminum cloth, the'shootconstituting one electrode and the warp the other electrode, at leastone of said electrodes comprising film forming metal, an electrolytepermeable cellulose spacer spirally wound around at least one of saidelectrodes so as to insulate it from metallic contact with the other,and an electrolyte in said spacer and in contact with both electrodes.

7. An electrolytic condenser comprising a metal cloth, the shootconstituting one electrode and the warp the other electrode, atleast oneof said electrodes comprising a film forming metal etched to increasethe eflective surface area I thereof, a dielectric oxide film formed onsaid etched electrodes, an electrolyte permeable cellulose spacer woundspirally around at least one of said electrodes so as to insulate itfrom the other electrode, and a viscous film forming electrolyteimpregnating said condenser structure. 8. An electrolytic condensercomprising a woven metal cloth immersed in an electrolyte, one set ofparallel strands of said cloth comprising the cathode, and a pluralityof sets of parallel strands transverse to said first set comprisinganodes, an insulating spacer directly spirally wound around at least oneset of parallel strands so as to insulate it from metallic contact withthe said transverse strands, an electrolyte in said spacer and incontact with said cathode and anodes.

9. An electrolytic condenser comprising a woven metal cloth immersed inan electrolyte, one set of parallel strands of said cloth comprising thecathode, and a plurality of sets of parallel strands transverse to saidfirst set constituting anodes, a coating on said cathode strands toinsulate said cathode from the anodes, and an uninsulated portion ofsaid cathode not in contact with said anodes but in direct contact withsaid electrolyte. 10. A dry electrolytic condenser comprising acontainer having therewithin an aluminum cloth, the shoot constitutingone electrode and the warp anotherelectrode, a spacer around at leastone of said electrodes so as to insulate-it from said other electrode,and a viscous electrolyte.

SAMUEL RUBEN.

